Define the term magnetic field of a magnet. How will you recognise it experimentally?

The space around a magnet in which if a magnetic substance such as small pieces of iron, are placed, they get attracted towards the magnet, is called a magnetic field.

Magnetic field of a magnet can be recognised by following experiment :

If a magnet is placed below a sheet of stiff paper and some iron filings are spread on it, then on tapping the sheet gently, the iron filings are found to arrange themselves in a definite pattern as shown in below figure.

The pattern of iron filings represent the magnetic field of the magnet where its direction is from north pole of magnet to its south pole and the magnetic field is not uniform as It is strong near the magnet while weak at a distance from the magnet.